1. Field of the Invention
The present invention relates to a sheet transporting apparatus disposed in a sheet transportation path. More particularly, the present invention relates to improvements of a sheet transporting apparatus in which, in a mode where the position of a side edge of a sheet is regulated, the sheet regulation position can be adjusted, and a sheet processing apparatus using such a transporting apparatus.
2. Background Art
A sheet processing apparatus such as a copier or a printer incorporates a sheet transporting apparatus which transports a sheet such as a paper sheet along a predetermined path. In a sheet transporting apparatus of this kind, a predetermined number of transportation rolls are arranged in a sheet transportation path. Each of the transportation rolls is rotatingly driven with using a motor or the like as a drive source. A sheet is transported from the upstream side to the downstream side in the transportation direction in accordance with the rotations of the transportation rolls.
In such a sheet transporting apparatus, when a sheet is transported in an inclined state, a so-called skew often occurs in the sheet. When a sheet in a skewed state is fed to a sheet processing section, a predetermined process is applied to the skewed sheet. When a skewed sheet is fed to an image output position of an image forming section, for example, an image which is inclined with respect to the sheet is output. Therefore, a sheet aligning apparatus for deskewing a transported sheet is usually used.
As one of aligning systems used in sheet aligning apparatuses, known is a system in which a skew is corrected by regulating the position of a side edge of a sheet. In the aligning system, a side guide is disposed on one side of a sheet transportation path along the transportation direction, and a skew roll is placed in the sheet transportation path. A transported sheet is laterally moved toward the side guide by the skew roll to butt against the side guide, thereby correcting the skew (side skew) of the sheet.
JP-A-7-206225 discloses an example of a sheet processing apparatus comprising such a sheet aligning apparatus. The apparatus has a configuration in which a sheet aligning apparatus is configured as one unit, the sheet aligning apparatus is extractably attached to the main unit of the sheet processing apparatus, and, under the attachment state, positioning is performed by butting a side guide of the sheet aligning apparatus against a stopper member of the main unit of the sheet processing apparatus.
In order to properly deskew a sheet in a sheet aligning apparatus, a reference line of a side guide must be placed strictly parallel to the sheet transportation direction, and a side edge of the sheet must extend along the reference line. When the reference line of the side guide is inclined with respect to the transportation direction, the sheet is transported with this inclination. As a result, the sheet is improperly deskewed.
By contrast, in the apparatus of JP-A-7-206225, since the sheet aligning apparatus is configured as one unit, the whole of the unit (sheet aligning apparatus) must be inclined in order to adjust the inclination of the reference line of the side guide. Therefore, the adjusting work is performed on a large scale and in a complicated manner, and fine adjustment is hardly conducted.
In order to eliminate the defects, the inventors of the invention provided a sheet transporting apparatus including: a sheet aligning section which has a reference member (such as a side guide) that is placed parallel to the transportation direction on one side of a sheet transportation path, and which causes a side edge of the sheet to elongate along a reference line set by the reference member; and an inclination adjusting section which has a rotation operating mechanism for rotatably supporting the reference member about a support shaft that is disposed in the transportation direction downstream from the sheet aligning section, and in which the inclination of the reference line with respect to the sheet transportation direction is adjusted by the rotation operating mechanism (see JP-A-2003-081490).
According to the configuration, the work of adjusting the inclination may be simplified as compared with the case where the whole unit is inclined.
In the configuration, the inclination of the reference member is adjusted by the single adjusting mechanism (rotation operating mechanism). When the adjusting step of the adjusting mechanism is finely set, therefore, fine adjustment after an initialization has been once set can be performed in a relatively simple manner. In a case where, for example, a transportation roll serving as a peripheral part of the sheet aligning apparatus is replaced with another one, when the inclination angle of the reference member is to be reinitialized, the work of adjusting the inclination of the reference member requires a prolonged time period because of the fine adjustment step of the adjusting mechanism, and the workability remains to be poor.
In the configuration, before a job, the inclination adjustment of the reference member can be uniquely performed in accordance with the kind of the job, the sheet size, and the environment. In the case where the inclination adjustment of the reference member is to be performed in the middle of the job, however, it is often to hardly cope with such adjustment, particularly when the inclination of the reference member must be adjusted by a large degree.
In double-side printing, for example, the same sheet is continuously transported, and the sheet transportation face is changed from a first face to a second face. In this case, the front-rear relationship of the sheet is usually inverted, and hence it is often necessary to change the reference line of the reference member before the regulation of the side edge position of the sheet.
In this case, the line of the side edge position of the sheet is inverted. Therefore, the adjustment width of the inclination of the reference member is inevitably increased. Since the adjustment is performed during a job, the time period for the inclination adjustment is restricted. As a result, the inclination of the reference member is hardly adjusted during the process of inversion-transporting a sheet.